Paper dispenser having a one-way spring clutch

ABSTRACT

The present invention concerns a paper dispenser comprising a housing holding at least one paper supply and a dispensing mechanism within said housing, the dispensing mechanism having a rotatable dispensing drum. The dispenser further comprises a turn knob coupled with the dispensing drum, the turn knob having an inner hub, and a wrap-spring clutch wrapped around the inner hub. The wrap-spring clutch has a first arias extending from it and being attached to a stationary point for causing the wrap-spring clutch to slightly unwind when the turn knob is rotated in the first direction. Characteristically of the invention, the wrap-spring clutch comprises a second arm extending from it, while a stopper is located in the second arm&#39;s rotational travel path in a second rotation direction for enabling the turn knob to be rotated in the second direction against a limited braking force.

FIELD OF THE INVENTION

The present invention relates to paper dispensers. More specifically,the present invention relates to paper dispensers having a turn-knob formanually rotating a mechanism dispensing paper web from a paper supply.

PRIOR ART

Paper dispensers having a dispensing mechanism with a dispensing drumare well known in the art. A dispensing drum commonly both feeds andcuts paper web into sheets and may be actuated in various ways, such asmanually using a turn knob, with an electric motor or by using a springloaded mechanism activated by a user pulling on a tail of the paper. Thedispensing drum holds a cutting knife which rapidly extends from thedrum, thus cutting the paper running along the periphery of the drum.Conventionally each revolution of the dispensing drum corresponds to thelength of a paper sheet, so that the cutting knife is extended andretracted once per each revolution. The dispensing drum is often also adriving element, meaning that its pulls paper from the paper supply andfeeds it further to a user.

Such kinds of paper dispensers are commonly equipped with a turn knobfor manually rotating the dispensing drum, even if the dispensing drumis primarily actuated by other means. Rotating the dispensing drummanually may be necessary in the event of an unwanted tear of the paper,particularly in the case that the dispensing drum is primarily actuatedby a user pulling on the tail of the paper. Another situation where thedispensing drum has to be rotated manually is when a new paper roll isintroduced to the dispenser and the paper web has to be threaded throughthe dispensing mechanism.

To avoid misuse, a turn knob is often coupled to the dispensing drum viaa one-way clutch allowing the turn knob to be rotated in only onedirection. Rotating the dispensing drum in the wrong direction can causethe paper web to unthread from the dispensing mechanism or even damagethe dispensing mechanism, depending on its structure. Also, equippingthe turn knob with a one-way clutch makes threading the dispensingmechanism more simple to the operator replacing a new paper roll to thedispenser as the turn knob can only be rotated in the correct direction.Common ways of implementing a one-way clutch are using a free wheelmechanism or a wrap spring clutch.

On the other hand, the dispensing drum might have to be rotated in anopposite direction during certain situations. For example, the paper webmay have to pulled out from the inlet side of the dispensing mechanismin connection with replacing a paper roll. Occasionally, a paperblockage may also occur, and again, the paper web may have to be pulledout of the dispensing mechanism from the inlet side. To enable such anoperation, the one-way clutch of a turn knob has to be releasable. Witha gear and pawl type ratcheting freewheel releasing the one-way clutchcan be done by simply turning the pawl outwards, but providing such arelease operation has been problematic with wrap-spring type clutches.

A particular problem associated with paper dispensers intended forpublic sanitary facilities is that they must withstand a certain amountof rough handling or even mischief. Turn knobs equipped with one-wayclutches have been discovered to be especially prone to breakage underexcessive forces. When a one-way clutch mechanism breaks the wholedispenser often has to be replaced.

OBJECTS OF THE INVENTION

An object of the present invention is to overcome the above-identifiedproblems associated with the dispensers of the prior art. A particularobject is to provide a paper dispenser having a turn knob that can befreely rotated in one direction while rotation in another direction isblocked unless a force exceeding a certain amount is applied to the turnknob in said another direction.

This object is achieved by a dispenser according to the invention asdescribed in the characterizing part of the accompanied claim 1. Furtherembodiments and objects of the present invention will come apparent fromthe dependent claims 2 to 4.

A paper dispenser according to the present invention overcomes thedrawbacks without the need for complex and expensive one-way clutchmechanisms.

BRIEF DESCRIPTION OF THE DRAWING

The invention is described hereafter with reference to the followingfigures, where:

FIG. 1 shows a perspective view of a portion of a dispensing mechanismand a wrap-spring clutch according to an embodiment of the invention;

FIG. 2 illustrates a turn knob and a wrap-spring clutch according to anembodiment of the invention;

It should be noted that the above mentioned figures are illustrated in asimplified manner for the purpose of clarity.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a side portion of a dispensing mechanism 1 of a paperdispenser and a wrap-spring clutch 2 can be seen. For illustrativepurposes the rest of the paper dispenser is not shown in FIG. 1. A pin 1a and a stopper 1 b protrude from the side portion of the dispensingmechanism 1, through which an axle 1 c of a dispensing drum (not shown)extends. The wrap-spring clutch 2, having a first arm 2 a and a secondarm 2 b extending from a central coil 2 c, is illustrated in a positioncorresponding to a normal operation condition of the paper dispenser.However, it should be noted that in normal operation condition of thepaper dispenser, the side portion of the dispensing mechanism 1 and thewrap-spring coil 2 would be at least partially covered by a turn knob ora housing, or both.

In FIG. 2 a perspective view of a turn knob 3 is illustrated. The turnknob 3 has an inner hub 3 a, around which the coil 2 c of the wrapspring clutch 2 is wrapped. In FIG. 2 the turn knob 3 is illustratedfrom a side facing the dispensing mechanism during operation of thepaper dispenser.

A dispenser according to the present invention comprises a housingcapable of holding at least one paper supply, such as a roll. Naturally,any paper supply providing a substantially continuous web can be used. Apaper web is led from the paper supply via a dispensing mechanism 1 tobe dispensed to a user through an opening in the housing. The dispensingmechanism 1 may also be used to cut the paper web in sheets prior todispensing. In the dispensing mechanism 1, the paper web is led to runalong a cylindrical circumference of a dispensing drum. As thedispensing drum is rotated, the paper web is pulled from the papersupply, into the dispensing mechanism 1 and fed towards the opening inthe housing to be dispensed. Furthermore, the dispensing drum may beequipped with an extending and retracting cutting knife for cutting thepaper web into sheets.

A turn knob 3 is directly connected to a center axle 1 c of thedispensing drum for enabling manual rotation. Other arrangements, suchas connecting the turn knob 3 to the dispensing drum via gears or belts,may also be used. According to an embodiment of the invention, theinside of an inner hub 3 a locks rotationally onto the axle 1 cextending axially from the dispensing drum's center axis, through theside portion of the dispensing mechanism 1. The wrap-spring clutch 2 isplaced around the hub 3 a. The inner diameter of the wrap-springclutch's central coil 2 c corresponds substantially to an outer diameterof said hub 3 a, so that the wrap-spring clutch 2 fits tightly onto theinner hub 3 a. Extending from the wrap-spring clutch 2, the first arm 2a is attached to a stationary point. In an embodiment according to FIG.1 the end of the first arm 2 a is bent to form a loop, which is wrappedaround the pin 1 a on the dispensing mechanism. Naturally, the first arm2 a could be attached to another stationary point, such as the housing.

The wrap-spring clutch 2 and its first arm 2 a are arranged so that whenthe turn knob 3 is rotated to turn the dispensing drum in the directionof its typical operation, the wrap-spring clutch 2 strives to rotatealong with the turn knob 3. However, the first arm 2 a being attached tothe pin 1 a, causes the first arm 2 a to pushed against the pin 1 a whenturn knob is rotated. This prevents the wrap-spring clutch 2 fromrotating along with the turn knob 3, and further exerts a force on thefirst arm 2 a causing the wrap-spring clutch 2 to slightly unwind, thusallowing the turn knob 3 and the dispensing drum to rotate freely in afirst direction. Consequently, when the turn knob 3 is rotated to turnthe dispensing drum in a second direction, i.e. in a direction oppositeto the first direction, the stationary first arm 2 a exerts a forcecausing the wrap spring clutch 2 to tighten around the inner hub 3 a. Asthe wrap spring clutch 2 tightens, the amount of force required torotate the turn knob 3 and the dispensing drum in the second directionbecomes increasingly larger, thus effectively preventing the turn knob 3and the dispensing drum from being rotated. Due to the resilient natureof the wrap-spring clutch 2, there is a small backlash before the turnknob 3 and the dispensing drum are prevented from being rotated. But asstated above, the amount of force required to rotate the turn knob 3 andthe dispensing drum in the second direction increases during thisbacklash.

On the other side of the wrap-spring clutch 2, opposite to the first arm2 a, there is a second arm 2 b extending from the wrap-spring's coil 2c. A stationary stopper 2 b is arranged along the rotational travel pathof the second arm 2 b in the second direction. The stopper 1 b may beattached to the dispensing mechanism 1 or the housing, for example. Whenthe turn knob 3 and the dispensing drum are rotated in the seconddirection, the second 2 b arm rotates along with the wrap-spring clutch2 during the backlash movement until it coincides with the stopper 1 b.At this point, the second arm 2 b pushes against the stopper 1 b andprevents the wrap-spring clutch 2 from tightening further around theinner hub 3 a. This arrangement effectively limits the amount of forcerequired to rotate the turn knob 3 and the dispensing drum in the seconddirection. The amount of force required to rotate the knob 3 and thedispensing drum in the second direction should be sufficiently largeenough to prevent undesirable rotation in said second direction, yetsmall enough not to cause breakage of any components, such as the pin 1a. The stopper 1 b should be located along the travel path of the secondarm 2 b in the second direction at such a distance that the amount offorce required to rotate the turn knob 3 and the dispensing drum is asdescribed above.

In an embodiment according to the invention, the second arm 2 b extendsoutside the periphery of the turn knob 3, suitably between said turnknob 3 and the dispensing mechanism 1. This arrangement enables thesecond arm 2 b to be pushed in the first direction, thus slightlyunwinding the wrap-spring clutch 2 and temporarily further reducing theamount of force required to rotate the turn knob 3 and the dispensingdrum in the second direction. When the second arm 2 b is no longerpushed in the second direction it automatically returns to its previousposition due to the resilient nature of the wrap-spring clutch 2. Suchfunctionality is especially suitable when the paper web has to be pulledout from the inlet side of the dispensing mechanism 1 during papersupply replacement. Advantageously, the dispensing mechanism 1 or thehousing is equipped with a pin or a notch for holding the second arm 2 bin a released position as described above.

In a further embodiment of the invention, the dispensing mechanism 1,the wrap-spring clutch 2, the turn knob 3 and the housing of the paperdispenser are arranged so that when the paper dispenser is in a normaloperation condition, i.e. the housing is closed, the wrap spring clutch2, namely its second arm 2 b, is located within the housing while theturn knob is located outside the housing. This enables the paperdispenser to be operated manually using the turn knob 3 while access tothe second arm 2 b is restricted only to people being able to open thehousing, such as maintenance personnel.

1. A paper dispenser comprising: a housing holding at least one papersupply; a dispensing mechanism within said housing for cutting anddispensing paper sheets from said at least one paper supply, saiddispensing mechanism having a rotatable dispensing drum; a turn knobcoupled with said dispensing drum for enabling manual rotation, saidturn knob having an inner hub extending axially towards said dispensingmechanism; a wrap-spring clutch wrapped around the inner hub of saidturn knob, said wrap-spring clutch having a first arm extending from itand being attached to a stationary point for enabling free rotation ofsaid turn knob in a first rotation direction by causing said wrap-springclutch to slightly unwind when said turn knob is rotated in said firstdirection, wherein the wrap-spring clutch comprises a second armextending from it, a stopper being located in the second arm'srotational travel path in a second rotation direction for enabling theturn knob to be rotated in said second direction against a limitedbraking force exerted on said inner hub by said wrap-spring clutchtightening around said inner hub.
 2. The paper dispenser according toclaim 1, wherein the second arm of said wrap-spring clutch extendsoutside the periphery of said turn knob.
 3. The paper dispenseraccording to claim 1, wherein a notch or a pin is provided for holdingthe second arm of said wrap-spring clutch in a displaced position in thefirst rotational direction
 4. The paper dispenser according to claim 1,wherein the second arm of said wrap-spring clutch is located within saidhousing while said turn knob is located outside said housing when saidhousing is closed.